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Lecture 36
Cancer
Ozgur Unal
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Do you know anyone with cancer?
What type of cancers have you heard of?
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Sometimes the system of quality control checkpoints in a
cell fails, because it is too complex.
When cells do not respond to the normal cell cycle control
mechanisms, a condition called cancer can result.
Cancer is the uncontrolled growth
and division of cells – a failure in the
regulation of the cell cycle.
When unchecked, cancer cells can
kill an organism.
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Cancer cells spend less time in interphase than do normal
cells  As long as they are supplied with nutrients they keep
growing.
Example:
Normal Stomach Cells
Cancerous Stomach Cells
Interphase
120 min
16 min
Prophase
60 min
15 min
Metaphase
10 min
2 min
Anaphase
3 min
1 min
Telophase
12 min
3 min
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The changes that occur in the regulation of cell growth and
division of cancer cells are due to mutations or changes in the
segments of DNA that control the production of proteins.
Various enviromental factors can affect the occurence of
cancer cells.
Substances and agents that are known to cause cancer are
called carcinogens.
Causes of cancer include:
Carcinogens such as tobacco
UV light and other harmful radiations
Stress etc.
http://www.newscientist.com/article/dn2213-potentialcarcinogen-revealed-in-french-fries.html
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Not every cell is destined to survive.
Some cells go through a process called apoptosis, or
programmed cell death.
Cells going through apoptosis actually shrink and shrivel in
a controlled process.
Example: Development of the
human hand and foot.
Example: Localized death of
cells that result in leaves falling
from trees in fall.
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Lecture 37
Stem Cells
Ozgur Unal
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Do you know this person?
Christopher Reeve became paralysis
after he fell down from a horse.
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Most of the multicellular organisms contain cells that are
specialized: Blood cells, muscle, nerve, bone cells etc.
In 1998, scientists discovered a way to locate a unique type
of cell in humans called the stem cell.
Stem cells are unspecialized cells that can develop into
specialized cells when under the right conditions.
There are two basic types of stem cells: Embryonic stem
cells and adult stem cells.
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Embryonic Stem Cells:
After a sperm fertilizes an egg, the
resulting mass of cells divides
repeatedly until there are 100-150 cells.
These unspecialized cells are called
embryonic stem cells.
If separated, each of these cells has
the capability of developing into a
wide variety of specialized cells.
Embryonic stem cell research is
controversial because of ethical
concerns about the source of the cells.
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Adult Stem Cells:
Adult stem cells are found in various tissues in the body
and might be used to repair the same kind of tissue in which
they are found.
Certain kinds of adult stem cells
can develop into different kinds
of cells, providing new treatments
for many diseases.
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